Day 02 Solution

2020/day02/day02.hs

@@ -0,0 +1,25 @@
+import Control.Arrow
+import Control.Monad
+import Data.List.Split
+
+main :: IO ()
+main = do
+  input <- lines <$> readFile "input"
+  print $ day2a input
+  print $ day2b input
+
+predicate :: String -> Bool
+predicate line = (l>=a) && (l<=b)
+    where c = head $ words p !! 1
+          [a,b] = map read $ splitOn "-" $ head $ words p
+          l = length $ filter (==c) str
+          [p,str] = splitOn ": " line
+
+day2a = length . filter predicate
+day2b = length . filter predicate2
+
+predicate2 :: String -> Bool
+predicate2 line = (str!!a==c) /= (str!!b==c)
+    where c = head $ words p !! 1
+          [a,b] = map (subtract 1 . read) $ splitOn "-" $ head $ words p
+          [p,str] = splitOn ": " line